CS3MESH4EOSC is a 3-year EU-funded project that addresses the challenges of the fragmentation of file and application services, digital sovereignty and the application of FAIR principles in the everyday practice of researchers. Initially, 7 major data services will be combined into ScienceMesh - a federated service mesh providing a frictionless collaboration platform for hundreds of thousands of users (researchers, engineers, students and staff). The service will offer easy access to data across institutional and geographical boundaries. The infrastructure will be gradually expanded and offered to the entire eduaction and research community in Europe and beyond. The initial service will connect SURFdrive, CERNBox, PSNCBox, CloudSTOR, Sciebo, owncloud@CESNET, SWITCHdrive and ScienceData. The CS3MESH4EOSC project will design, build and deploy the necessary technology to achieve this. CS3MESH4EOSC grew out of the CS3 community consisting of infrastructure builders and providers from the academic sector - servicing and supporting science, education and research.